The synthesis, screening, and evaluation of novel radiosensitizers is the overall objective of this project with the goal being the synthesis of a compound having a greater therapeutic effect and less toxicity than misonidazole, the radiosensitizer currently being evaluated in clinical trials. All compounds designed and synthesized are to be characterized physically and chemically and supplied to the NCI in gram quantities. The cytotoxicity and radiosensitization of each compound will be tested in vitro. In vivo efficacy of selected radiosensitizer compounds will be evaluated in three different tumor systems, each measured by a separate endpoint and compared directly with misonidazole in the same test systems. The search for non-affinic and non-nitro compounds is encouraged.